Lithium ion batteries, lithium air batteries and lithium sulfur batteries are well-known rechargeable devices for storing electric energy. Lithium ion batteries comprise an electrolyte composition containing a solvent, a conductive salt and, often, additives. The solvent is an aprotic organic solvent which serves to dissolve the conductive salt. See, for example, WO 2007/042471 which provides information concerning suitable solvents. Suitable conductive salts are known in the art. LiPF6 is a preferred conductive salt.
Capacitors are widely used devices for storing electrical energy. Among the various types of capacitors are electrochemical capacitors and electrolytic capacitors.
A hybrid supercapacitor is an electrochemical energy storage device that employs two different electrode types, the difference between the electrodes generally being in capacity or composition, and an electrolyte composition.
The optimization of the electrolyte compositions in hybrid supercapacitors still offers a significant potential to improve the performance properties of such systems.
Additives improve the properties of lithium ion batteries, e.g. by extending the cycle life. Fluoroalkyl alkyl carbonates, e.g. fluoromethyl methyl carbonate, and fluorinated alkyl carbamates are known solvent additives for lithium ion batteries. WO 2011/006822 discloses the manufacture of 1-fluoroalkyl (fluoro) alkyl carbonates and carbamates. However, there is still a demand in the art for improved additives for lithium ion batteries as well as for improved methods for the manufacture of additives.
Accordingly, the objective of the present invention is to provide methods for the manufacture of fluorinated cyclic carbonates that are advantageous in terms of overall yield and/or purity of the desired product, the energy consumption of the manufacturing process, the safety requirements of the process, the ease of work-up, and/or the side-product profile.
Furthermore, it is an objective of the present invention to provide improved additives for lithium ion batteries, lithium air batteries, lithium sulphur batteries or supercapacitors. The compounds of the present invention provide advantages like modifying the viscosity or reducing the flammability. Another advantage is the modification of the electrodes under formation of beneficial films or a solid electrolyte interphase (SEI). Furthermore, the compounds of the invention advantageously lead to a better wettability of materials used in lithium ion batteries such as in particular a separator. The compounds of the invention can suitably assist in the protection against over-charging, for example, by serving as a redox shuttle. Yet another advantage is an increase in stability of the electrolyte composition, e.g. in presence of copper substrate, which can be formed by possible degradation of certain current collector materials.
Furthermore, the compounds of the present invention advantageously show a higher stability towards reduction and/or oxidation. Alternatively, the compounds of the present invention advantageously show a high stability towards oxidation while having a relatively low stability towards reduction. This property can lead to an increased performance of the battery, e.g. by modifying the electrodes of the battery, specifically by the formation on a protective layer on the electrode. The inventive products can also advantageously lead to an improved performance when used together with a silicon anode in a lithium ion battery. Additionally, the inventive products advantageously allow the voltage of the batteries comprising electrolytes comprising products to be higher, preferably equal or higher than 4.4 V.
Additionally, the compounds of the present invention may increase energy density of a supercapacitor, their power density or their cycle life.